Method of producing lead oxide



' EVANS,- a; citizen pf the/United States of;

' sulphate in admixture with finely divided Patented Jan. 19, 1926. i 1

- UNITED s r SAMUEL iransrrat'nrlvhiws, or Essex rents, New JERSEY."

amison or rnonircme manoxmnx No Draivifign- To-allwkom a:

Be it known that I, -SAMUEL'MaRsHALL America; and resident of Essex Fell's,.in the county of Essex,"in the state of New J ersey', have invented a certain new and useful Improvement inflMet'hods of Producing Lead Oxide, of which the following is "a true and exact description." j Y Y My invention relates generally to the treatment ofleadv sulphate or lead material containing lead sulphate, primarily '-to se;

cure the complete conversion of the sulphate into lead hydrgxid or carbonate from-which other lead products: canbe made byany known orconvenient'treat-ment. 'More par- .ticularly' my invention relates to the .pro-

duction mm the material of storage battery plates," which contains a large pioportion of lead sulphate,- of lead oxide free from sulphate. 1

will be converted into lead h droxidfbut ordinarily thereaction with t e lead sulphate is not completeforreasons explamed in the patent to Hughes No. 1,033,405 'of July 23,1912, which describesa method involving the trituration' of the reacting ma- 'te'rials fo'r-efiecting a ,complete conversion of the lead sulphate into jthe desired products.

lead sulphate, or lead. material including lead sulphate, of a small -ercentage of finely divided'metallic lead, wil when the mass is' treated with arhotsolution of an alkaline base,or an alkaline carbonate, result in the com lete conversion of the lead sulphate -to the ydroxide or carbonate 'without-tritura' tion. The metallic lead in this treatment may be, said to/act asa reducing agentor as a catalyst and is, I believe, ractically unat itappears affected by the treatment in t in the product;

Broadly speaking, my invention consists in the process of treating finely divided lead lead with a hot alkaline-base solution to convert the, sulphate into a hydrate or car bonate.

More particularly I have in "view the treatment of the paste portions of storage battery plates, primarily for the conversion,

of-its-lead sulphate component into a by- It is knownz thatl'ead sulphate treated witha'n' alkaline base such as caustic. soda' My invention is based on my -diseovery' that the-presence in a mass of fi-nel d1V 1ded Application liled Me.rch -5, 1923 Serial 623,022.

plates or'other uses, and my invention further consists inthe described treatment of PATENT OFFICE;

the battery p'late material for this purpose involving as a-pa'rt. "of the process mygeneral method of convertingthe lead s ph into a hydrate or carbonate;

. 'Us'edbattery plates are-made up' 'phate, lead peroxide and 'sponge lead, and I first separate the f-riable v from the grids by treating the plates'in a aste material escape. This material" includes ;'a' considergrids supporting material, originally a plied as a.paste, and comprising lead-s15 tumbling barrel made with smail holes through which the friable salts, etc.,'can' able portion of-the spon'ge lead." The material escaping through the holes in the'bar:

rel I treat in a sponge lead to a 'finestate of-division'and ulverizer so as to bring the salts and oxi es and a portion of the from this finely divided material I ,separate-any comparatively large i pieces of lead Z-wliich can be subsequently smelted with'the pieces of: grid left in the'barrel. The lead separated from the paste material I smelt first mixing with it 'a-small amount of soda ashjt'o fiuxthe small'percenta'ge of .lead 'sul' hateadheringas a dust or other- -wise tohe lead. I

The mixture of finely "divided lead-S 11;

phate, lead peroxide and small amount of finely divided sponge leafd is analyzed to determine the amount of lead sulphate present and to a batch' of. such material I add analkaline, base preferably caustic soda -or soda ash, in amount somewhat in excess of the'chemic'alequivalent of lead sulphate present. In practicel have used twenty to a tank'of boilin' water, the temperature of which-is lowere by the batch but rapids ppercent excess. I-then charge the batch-in sly raised' again to the boiling point by I steam, ,I' find it advantageous to then. turn 7 off the steam-and permit the contents of the tank .to cool to about 'or below-150 ,F.

and .to then turn on the steam slowly,"

gradually raising the temperature to 212 F. and holding that temperature for about thirty minutes. .At the end of this time I' find. that the reaction converting the lead" sulphate to leadhydroxid or lead caibonate is mp te; The alkali compound is, of

' where lead carbonate, if present, ives off its ()0 and becomes lead monoxi e, PbO, the lead peroxideis reduced'to PbO, and the s onge leadis oxidized to PbO, the result ing a pure lead oxide suitable for commercial use.

Where leadsulphate from other sources than battery plates is to be converted into a 'h drateor carbonate, I mix with the sulp ate in a' fine state of division a small percentage of finely'divided lead and treat the mixture in the same way I have described.

Having now described ,my invention, what I claim as new and desireto secure by LettersPatent, 1's;-

phate, into a different lead "compound which consists in mixing the sulphate in a fine state of division with a small percentage of finely divided metallic leadand boiling the mixture in a solution of an alkali-metal base to effect an exchange of bases.

2: The method of treating storage-battery plates for the economic recovery of the-plates, .treating the separated lead sultheir component' arts which consists in I separating the lea grids and a large'pro portion of the sponge lead from the lead sulphate and. lead peroxide components of phate, lead peroxide and-sponge lead, all'in a state ,o'f fi-ne division, ,with a hot solution of an alkali-metalbase until an exchange ofbases is effected, washing the treated ma:

terialto remove soluble salts and heating the residue in'an oxidizing furnace to convert its componentsinto lead oxide.

3. The method of treating storage bat-- teryplates for the economicrecovery of their component parts 'which' consists in separating the lead grids and a lar e proportion. of the sponge leadfrom t elead sulphate and lead peroxide components of the plates, treating the separated lead 'sul-' in a state of line division, withv a hot solu- V tion; of an alkali-metal. base until an 'ex- 1.- The method of converting lead sulchange of bases is elfected, washing the .treated. material to removesoluble salts,

heating the residuein an oxidizing furnace to convert its components into lead oxide and. smelting the lead separated from the .l

phate, lead peroxide and sponge lead, all, 

